An ideal communication system would be capable of instantly transmitting a seemingly unlimited amount of information over a particular communication channel covering any distance within a period of time imperceptible to the user of the information, whether human or machine. Of course, communication of information in any real system is subject to a number of often complementary or related constraints. Optimization of a communication system for any particular application involves compromises of conflicting constraints which likely include economic considerations.
Communication channels and associated communication protocols may be described by any of a number of parameters or operating characteristics which ultimately affect the quality and quantity of information which may be communicated. The rate or throughput of information transferred, or the criticality or importance of the information, may control the design or selection of a particular communication system or communication media. In general, higher quality and higher rate communication channels are more expensive to utilize because of the increased portion of the total available bandwidth which must be allocated to a fewer number of individual applications. Thus, economic considerations impose use of the lowest rate and lowest quality communication system or channel which is acceptable for a particular application.
The selected communication channel or protocol may impose significant delays between generation of information at one location and receipt of information at another location. Such delays make various types of communication media and channels unacceptable for interactive applications such as remote computing and video teleconferencing which impose constraints of real-time or near real-time responsiveness to be considered high quality.